Traditional paper pricing labels for products presented on a shelf are being replaced by digital units. Digital units have an LCD display driven by digital logic. They typically are installed on the edge of the retail shelf. In some instances these digital units are capable of radio communication similar to the active radios commonly used by people, for example in car radios and cell phones.
Active radio transmission is well known technique of radio transmission where an active power source generates a radio-frequency (RF) wave that is modulated with information and the RF wave excites an antenna. Electro-magnetic radiation propagates from the transmitting antenna to a receiving antenna. A receiver, which may be either active or passive devices, collects the signal, demodulates it, and presents the demodulated information to the user. The advantage of using active radio transmission is that because of the active power source, signal strength is typically good and, hence, there is improved transmission range. However, the use of an active power source results in the need for a larger power supply and generation of heat, both of which are concerns in compact circuitry designs.
Other known methods of communication include a backscatter transceiver having a receiver and a transmitter. Backscatter transmission is a technique whereby signals are sent with typically lower power consumption than comparative techniques. The system requires a RF source and the transmitter. The source sends a radio wave over the air. The radio wave propagates from the source to the transmitter's antenna. What is commonly called a backscatter receiver is actually a diode demodulator for non-constant amplitude carrier reception. A backscatter transmitter does not have an active power source to generate an RF wave(s). An advantage of the backscatter transceiver is low power consumption and, hence, an effective design alternative. However, the problem with the backscatter transceivers is that the signal strength is low and, hence, the range is very limited. Thus, backscatter transceivers are not always effective when longer transmission range is desired.
Therefore what is needed is a system and method that communicate using radio communication using minimal power with low heat dissipation to allow for a compact and cost effective design solution, while providing for effective communication range based on the ability to generate strong radio communication signals when required.